Sets the number of display columns in the output of ,backtrace
and ,locals to cols. If cols is not given, the width
of the terminal is used.

The next 3 commands work at any REPL.

REPL Command: breakproc

Set a breakpoint at proc.

REPL Command: break-at-sourcefile line

Set a breakpoint at the given source location.

REPL Command: tracepointproc

Set a tracepoint on the given procedure. This will cause all calls to
the procedure to print out a tracing message. See Tracing Traps, for
more information.

The rest of the commands in this subsection all apply only when the
stack is continuable — in other words when it makes sense for
the program that the stack comes from to continue running. Usually this
means that the program stopped because of a trap or a breakpoint.

REPL Command: step

Tell the debugged program to step to the next source location.

REPL Command: next

Tell the debugged program to step to the next source location in the
same frame. (See Traps for the details of how this works.)

REPL Command: finish

Tell the program being debugged to continue running until the completion
of the current stack frame, and at that time to print the result and
reenter the REPL.